长治市2013年7月异常降水特征及环流背景分析

利用2013年7月长治市11个县旬月报资料、24 h降水量(观测站和乡镇自动雨量站)资料、历史资料以及美国NCEP再分析资料,对长治市7月旬月降水量、降水日数、暴雨日数、暴雨过程、最大雨强及环流背景进行了分析。结果表明,全市7月平均降水量为389.4mm,较历年同期(127.4mm)偏多262.0mm(206%),全市11个县观测站降水量均为有气象记录以来的最大值;7月全市各县观测站暴雨总站次为26次,是暴雨站次年极值的2.2倍,全市乡镇自动雨量站暴雨总站次为47次,是暴雨站次年极值的4倍。其环流特征表象为:欧亚中高纬呈西低东高异常分布,极涡中心位于极点附近,较常年同期略偏强;西太平洋副热带高压西段强度较常年同期偏强;季风槽位于85°E附近,影响印度半岛和孟加拉湾一带,较常年同期偏强。

Abnomaly Characteristics of July 2013 Precipitation in Changzhi and Its Analysis of Circulation Background

In this paper, using July 2013 Changzhi 11 counties monthly data, 24 h precipitation, from observation stations and township automatic rainfall stations, data, historical data, and the NCEP reanalysis data, monthly precipitation for Changzhi in July,precipitation days, the number of storm days, storm rainfall process, maximum rainfall intensity and circulation background were analyzed. The results showed that： the city in July average rainfall was 389.4 mm, compared to the same period of the calendar year（127.4mm）was262.0mm（206%）more,the precipitation of thecity＇s 11 counties observation stations were all the maximum precipitation since meteorological records; July the city counties observatory storm terminus times were 26, which was 2.2 times of storm station annual maximum, the city＇s townships automatic rainfall stations rainstorm terminus times were 47, was 4 times of storm station annual maximum.Its circulation features was：（1）the Eurasian high latitudes west low to east high abnormal distribution, polar vortex located near the center of the pole, compared to the same period was a little bit stronger.（2） the strength of the western part of the western Pacific subtropical compared to the same period a bit stronger.（3）the monsoon trough near 85° E, affecting the Indian peninsula and the Bay of Bengal area, compared to the same period a little bit stronger.